Quorum-sensing based bacteriocin production is down-regulated by N-terminally truncated species of gene activators |
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Authors: | Daniel Straume Morten Kjos Ingolf F Nes Dzung B Diep |
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Institution: | Laboratory for Microbial Gene Technology, Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Science, PO Box 5003, 1432, As, Norway. |
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Abstract: | Down-regulation of quorum-sensing based pathways is an important but yet poorly understood process in bacterial gene regulation.
In this study, we show that the gene regulator plnC not only acts as an activator gene in the quorum-sensing based bacteriocin production in Lactobacillus plantarum C11, but it also concurrently codes for truncated forms that were shown to repress bacteriocin production. By amino acid
N-terminal sequencing and DNA sequence analysis, the truncated species of PlnC are believed to be translated from alternative
start codons located in the so-called receiver domain of the regulator. To analyse the structure–function relationship of
truncated species of PlnC, we performed a series of systematic truncation mutations: ten in the receiver domain, one in the
hinge region and two in the C-terminal DNA-binding domain. It was revealed that any truncation mutation containing a disrupted
receiver domain together with an intact DNA-binding domain displayed a repressive effect on bacteriocin production. Such a
gene repression mechanism mediated by truncated regulators was also found in two other quorum-sensing based bacteriocin systems
(spp in L. sakei LTH673 and NC8-pln in L. plantarum NC8), suggesting that this mode of repression might represent a common means applied by bacteria to down-regulate certain
quorum-sensing based pathways.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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Keywords: | Quorum-sensing Gene regulation Repression Three-component regulatory system Bacteriocins |
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